United States or Sudan ? Vote for the TOP Country of the Week !
He also described the "moraines" of the ancient glaciers, and the rounded masses of polished rock, called in Switzerland "roches moutonnees." His views respecting the old extinct glaciers of North Wales were subsequently confirmed by Mr. Darwin, who attributed the transport of many of the larger erratic blocks to floating ice. Much of the Welsh glacial drift had already been shown by Mr.
And you will see that the knolls of serpentine rock, or at least their backs and shoulders towards Lochnagar, are all smoothed and polished till they are as round as the backs of sheep, "roches moutonnees," as the French call ice-polished rocks; and then, if you understand what that means, you will say, as I said, "I am perfectly certain that this great basin between me and Lochnagar, which is now 3000 feet deep of empty air was once filled up with ice to the height of the hills on which I stand about 1700 feet high and that that ice ran over into Glen Muick, between these pretty knolls, and covered the ground where Birk Hall now stands."
On its western declivities are found a group of well-characterized moraines, canyons, and roches moutonnees, all of which are unmistakably fresh and telling. The moraines in particular could hardly fail to attract the eye of any observer.
Agassiz found the rounded and moutonnees surfaces and the general modeling of the outlines of ice no less marked here than in the Strait; and in a ramble over the hills above the anchorage, M. de Pourtales came upon very distinct glacial scorings and furrows on dikes and ledges of greenstone and syenite.
The greater number of the green chloritic fragments in trains 5 and 6 have evidently come from the ridge A, and a large proportion of the whole from its highest summit d, where the crest of the ridge has been worn into those dome-shaped masses called "roches moutonnees," already alluded to, and where several fragments having this shape, some of them 30 feet long, are seen in situ, others only slightly removed from their original position, as if they had been just ready to set out on their travels.
Every characteristic feature, known in the Alps as the work of the glaciers, was not only easily recognizable here, but as perfectly preserved as anywhere in Switzerland. The rounded knolls to which De Saussure first gave the name of roches moutonnees were smoothed, polished, scratched, and grooved in the direction of the ice movement, the marks running mostly from south to north, or nearly so.
Furthermore, the horizontal sections of separate mountains, standing isolated in the great valleys, are lens-shaped like those of mere rocks that rise in the channels of ordinary canyon glaciers, and which have been overflowed or pastflowed, while in many of the smaller valleys roches moutonnees occur in great abundance.
Drumlins are made of ground moraine. They were accumulated and given shape beneath the overriding ice, much as are sand bars in a river, or in some instances were carved, like roches moutonnees, by an ice sheet out of the till left by an earlier ice invasion.
Word Of The Day